roottilårsakanalyse

Roottilårsakanalyse is a term encountered in some Danish-language statistical discussions describing an approach to analyzing yearly data by examining the roots of a time-series model's characteristic equation. The aim is to understand annual cycles, trends, and persistence by linking root properties to dynamic behavior.

In practice, the method involves fitting a linear time-series model to annual observations, such as an ARIMA or state-space representation, and computing the roots of the model's characteristic polynomial. Complex conjugate roots indicate oscillatory components, while the modulus (absolute value) of a root relates to damping or growth, and the argument corresponds to cycle length. Roots near the unit circle suggest persistent or slowly decaying patterns.

The typical workflow is: gather reliable yearly data; select a suitable model and estimate its parameters; extract the roots and interpret their implications for seasonality and trend; and use the root information to inform forecasting or comparative analysis across periods.

Applications of roottilårsakanalyse span economics, climatology, ecology, and agriculture, where yearly cycles and long-run persistence are important. The term is not widely standardized and may overlap with conventional time-series analysis and spectral methods; in many sources, the same ideas are discussed without using the term.

See also: time-series analysis, ARIMA, spectral analysis.